The CB1 receptor is one of the most abundant neuromodulatory receptors in the brain, and is expressed at high levels in the hippocampus, cortex, cerebellum, and basal ganglia (e.g., Wilson et al., Science, 2002, vol. 296, 678-682). Selective CB1 receptor antagonists, for example pyrazole derivatives such as rimonabant (e.g., U.S. Pat. No. 6,432,984), can be used to treat various conditions, such as obesity and metabolic syndrome (e.g., Bensaid et al., Molecular Pharmacology, 2003 vol. 63, no. 4, pp. 908-914; Trillou et al., Am. J. Physiol. Regul. Integr. Comp. Physiol. 2002 vol. 284, R345-R353; Kirkham, Am. J. Physiol. Regul. Integr. Comp. Physiol. 2002 vol. 284, R343-R344), neuroinflammatory disorders (e.g., Adam, et al., Expert Opin. Ther. Patents, 2002, vol. 12, no. 10, 1475-1489; U.S. Pat. No. 6,642,258), cognitive disorders and psychosis (e.g., Adam et al., Expert Opin. Ther. Pat., 2002, vol. 12, pp. 1475-1489), addiction (e.g., smoking cessation; U.S. Patent Publ. 2003/0087933), gastrointestinal disorders (e.g., Lange et al., J. Med. Chem. 2004, vol. 47, 627-643) and cardiovascular conditions (e.g., Porter et al., Pharmacology and Therapeutics, 2001 vol. 90, 45-60; Sanofi-Aventis Publication, Bear Stearns Conference, New York, Sep. 14, 2004, pages 19-24).
However, there is still a need for improved cannabinoid agents, particularly selective CB1 receptor antagonists, with fewer side-effects and improved efficacy. It is therefore an object of the present invention to provide substituted piperazines useful in the treatment of diseases or conditions mediated by CB1 receptors.
WO 95/25443, U.S. Pat. No. 5,464,788, and U.S. Pat. No. 5,756,504 describe N-arylpiperazine compounds useful for treating preterm labor, stopping labor, and dysmenorrhea. However, none of the N-aryl piperazines exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
WO 01/02372 and U.S. Published Application No. 2003/0186960 describe cyclized amino acid derivatives for treating or preventing neuronal damage associated with neurological diseases. However, none of the 3-aryl piperazine 2-ones exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
WO 96/01656 describes radiolabelled substituted piperazines useful in pharmacological screening procedures, including labeled N-aryl piperazines. However, none of the N-aryl piperazines exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
U.S. Pat. No. 5,780,480 describes N-aryl piperazines useful as fibrinogen receptor antagonists for inhibiting the binding of fibrinogen to blood platelets, and for inhibiting the aggregation of blood platelets. However, none of the N-aryl piperazines exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
WO 03/008559 describes choline analogs useful for treating conditions or disorders. However, the only substituted piperazine derivative exemplified is N-(2-hydroxyethyl)-N′-(2-pyridylmethyl)-piperazine.
JP 3-200758, JP 4-26683, and JP 4-364175 describe N,N′-diarylpiperazines (i.e., 1,4-diarylpiperazines) prepared by reacting bis(2-hydroxyethyl)arylamines with an amine such as aniline. However, no 1,2-disubstituted piperazines are exemplified.
WO 97/22597 describes various 1,2,4-trisubstituted piperazine derivatives as tachykinin antagonists for treating tachykinin-mediated diseases such as asthma, bronchitis, rhinitis, cough, expectoration, etc. However, none of the 1,2,4-trisubstituted piperazine derivatives exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
EP 0268222, WO 88/01131, U.S. Pat. No. 4,917,896, and U.S. Pat. No. 5,073,544 describe compositions for enhancing the penetration of active agents through the skin, comprising azacyclohexanes, including N-acyl and N,N′-diacylpiperazines. However, none of the N-acyl or N,N′-diacylpiperazines exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
U.S. Pat. No. 6,528,529 describes compounds, including N,N′-disubstituted piperazines, which are selective for muscarinic acetylcholine receptors and are useful for treating diseases such as Alzheimer's disease. However, none of the N,N′-disubstituted piperazines exemplified therein have an aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
NL 6603256 describes various biologically active piperazine derivatives. However, none of the piperazine derivatives exemplified therein have a substituted aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.
Wikström et al., J. Med. Chem. 2002, 45, 3280-3285, describe the synthesis of 1,2,3,4,10,14b-hexahydro-6-methoxy-2-methyldibnzo[c,f]pyrazine[1,2-a]azepin. However, none of the piperazine intermediates described therein have a substituted aryl and/or heteroaryl substituent at both the 1- and 2-positions of the piperazine ring.